Nozzle for injection moulding tool and nozzle arrangement

ABSTRACT

A nozzle  10  for an injection mold has a nozzle body  12  which can be mounted on a mold or manifold and in which at least one duct  22  for molten material is provided which opens at a terminal side at, or in, a nozzle tip  26.  In order to be able to realize extremely small pitches in two independent directions in space, the nozzle body  12  has at least one substantially plane lateral surface  14, 15  which carries or accommodates in a plane 2D-type joining and/or arrangement a heating and/or cooling device  28, 28′  for the molten material. In a special embodiment, the nozzle  10  within in a row of nozzle R are located next to each other in very close relationship, and two opposing lateral surfaces S or the row of nozzles R are provided with heating and/or cooling devices  28, 28′ , which are adapted to be connected in groups to a heating or cooling circuit via a common external terminal.

The invention relates to a nozzle for injection molds and to a nozzleassembly.

BACKGROUND ART

Nozzles for hot runners or cold runners are generally known. They areused in injection molds for feeding a melt flow at a predefinedtemperature under high pressure to a separable tool block (mold cavity).For example, in order to prevent a hot plastics flow from prematurecooling within the nozzle, electric heating means are provided—asdescribed in DE-U1-295 01 450—which concentrically surround the nozzlebody or a duct located therein in order to keep the plastics melt at thedesired temperature. However, if for example reactive polymers areprocessed, it is necessary to cool the nozzle body for ensuring that themass to be processed will not exceed a specific temperature as it entersthe mold cavity. A thermosensor is normally used to probe thetemperature.

In the case of hot runner nozzles, the nozzle body and the heatingelement are usually separate component parts, the heating element beingintegrated with the thermosensor in a jacket to be pushed onto thenozzle body periphery. As disclosed in DE-U1-89 15 318, DE-U1-295 07 848or U.S. Pat. No. 4,558,210, the surrounding element may be a rigid unitfixed onto the nozzle body in an axial direction by holding or clampingmeans. Alternatively, flexible heating strips or mats are used which areattached to the perimeter of the nozzle body (see e.g. EP-B-0 028 153 orWO 97/03540).

SUMMARY OF THE INVENTION

An essential drawback of these generally detachable heating devices istheir usually inefficient heat transfer from the heating element to thenozzle body. Now in order to protect the heating means from overheating,it is necessary to increase their dimensions whereby the overallassembly size and thus the space required in the mold will alsoincrease. Furthermore, there are problems with the linear temperaturedistribution in the duct walls. Rarely will these have a constanttemperature over the entire length of the duct. By reason of theincreased heat dissipation at the tip of the nozzle, an adequate powerdensity and thus constant temperature at this point can only be achievedwith relatively high expenditures.

In numerous fields of applications, it will irrespectively thereof benecessary to inject into separate cavities in order to manufacture anumber of articles simultaneously or more complex components. To thisend, nozzles for hot runners or cold runners are mounted at defineddistances parallel to each other in a manifold or manifold block.However, due to the concentric arrangement of the heating or coolingmeans on the nozzles and to the fact that their electric terminalsusually project laterally from the nozzle casings, the nozzles cannot bepositioned closely to each other, which will be problematic where cavityspacings are small or gating points are directly adjacent.

For remedy, it was attempted to attain reduced cavity spacings bypositioning the nozzle duct and the heating means laterally, e.g. in ahot runner nozzle as described in DE-U1-296 10 268. However, thisreduces the width of the nozzle in a preferred direction only,irrespective of the width of the heating means which still is rathervoluminous. Another drawback is the fact that heat will dissipate toonly one side of the flow melt, thus possibly causing unbalancedtemperature distributions in the duct. Adaptation and control of thepower input required is only possible within limits since the powerdensity of the heating means, often a heater cartridge, can be tuned toonly one particular application at a time. Pluralities of plugconnectors and elaborate cable lines not only require additional spacebut also extra fitting work, in particular where the terminals of theheating means used are in the interior of the nozzle assembly.

It is an object of the present invention to overcome these and otherdrawbacks of the prior art and to provide a nozzle for an injection moldpermitting uniform heat transfer and temperature distributioncharacteristics within the nozzle body and requiring little space whenmounted to a mold. In an economical manner, a structure is to beobtained which can be manufactured and installed with a minimum ofexpenditures and which ensures long-term operational reliability.

Another important object of the invention is to provide a nozzleassembly containing an arbitrary number of closely packed hot runnernozzles or cold runner nozzles, which assembly is suited to be cheaplyproduced with simple means and to be quickly installed. Furthermore, thenozzle interior is to provide uniform heat transfer and temperaturedistribution characteristics.

In a nozzle for an injection mold comprising a nozzle body adapted to bemounted onto a mold or manifold, the nozzle body having at least oneduct for a melt flow which duct opens at or in a nozzle tip, andcomprising a heating and/or cooling means for the melt flow, theinvention provides that the nozzle body has at least one substantiallyplane lateral face which supports or accommodates said heating and/orcooling means in a full-faced engaging and/or joining arrangement.

This integral connection between the heating or cooling means and saidlateral face in the hot runner nozzle guarantees constant optimal heattransfer from the heating unit to the nozzle body, which will be heatedextremely uniformly and precisely. Due to the full surface engagement orjoining of the heating means with the plane or slightly curved lateralsurface of the nozzle body, the hot runner nozzle has extremely smalloverall dimensions compared with conventional designs, whilst exhibitingalmost identical performance. The same applies to a cooling meansintegrated with the nozzle body, which cooling means is according to apreferred embodiment directly enclosed in the nozzle body and is flushtherewith. Heat transfer from the hot medium to the cooling means isalways optimal.

Since the heat is generated and dissipated directly at the lateralsurface of the nozzle body to be heated, the power density of such aheating unit can be raised considerably and overheating of the usuallysensitive heating elements is reliably avoided. Furthermore, there is noneed for elaborate control means to regulate delays caused by thermalinertia of the flow melt. The plastics composition in the flow duct israpidly and precisely heated, which has a favorable effect on theoverall production process. Particularly uniform heating or cooling isachieved where two opposing lateral faces are provided with at least oneheating and/or cooling means.

Another substantial advantage of the invention consists in that the hotrunner or cold runner nozzle has extremely small dimensions due to theheating or cooling means being located directly against or in the nozzlebody. This applies particularly if the heating means positioned at theplane and/or at least partially curved lateral surfaces of the nozzlebody is designed as a thin lamina heating unit.

According to another embodiment of the invention, temperature sensing iscarried out preferably in the same plane where heating or cooling iseffected so that no additional space is required. Heating or coolingmeans and the thermosensor can be provided on the nozzle body in likemanner and in a single manufacturing operation whereby production issimplified considerably.

In a nozzle assembly for injection molds comprising at least twonozzles, each having a nozzle body capable of being mounted on a mold ormanifold, the nozzle body including at least one melt flow duct thatopens at or in a nozzle tip, and comprising a heating and/or coolingmeans for the melt flow, the invention provides that the nozzles form anozzle row within which they are disposed closely and parallel to eachother, said nozzle row having at least one substantially plane lateralsurface for full-faced engagement or joining to said heating and/orcooling means.

Owing to this extremely compact and space-saving design, the tips of theindividual nozzles are very closely packed. Such a row of nozzles allowseffortless injection into a number of mold cavities or simultaneouslyinto several gating points, the cavity spacings or the distances betweenthe gating points reaching extremely small values of down to 5 mm in anydirection. A comb-like arrangement of the nozzles within the rowguarantees that the nozzles are at least partially set at distances fromeach other, whereby different thermal expansions are allowed for.Moreover the flat nozzle body, which as a whole is preferably anintegral unit, can be rapidly and conveniently mounted on a manifold ina single operation so that handling is considerably simplified.

Various spaced grids between the hot runner and/or cold runner nozzlescan be realized by disposing a plurality of individual nozzles or rowsof nozzles side-by-side within a single manifold. The individual nozzlesof these flat bodies thus form a battery with extremely small nozzlespacing in both transverse and longitudinal directions. Since eachindividual nozzle is provided with e.g. flat heating means which arepreferably interconnected on the lateral faces of the flat bodies andare provided with a common terminal, the inner nozzles of a battery arealso readily supplied with the necessary heating energy; that was notpossible with previous solutions. The entire problem of makingconnections for the heating or cooling units is considerably simplified,which is beneficial not only for the fitting work.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, details, and advantages of the invention may begathered from the wording of the claims and from the followingdescription of working examples with reference to the drawings wherein:

FIG. 1 is a side view of a hot runner nozzle,

FIG. 2 is a top view of the hot runner nozzle of FIG. 1,

FIG. 3 is an enlarged cross-section through the hot runner taken alongA—A in FIG. 1,

FIG. 4 is a side view of a hot runner nozzle with replaceabletemperature sensor,

FIG. 5 is a top view of the hot runner nozzle of FIG. 4,

FIG. 6 is a side view of a row of nozzles,

FIG. 7 is a top view of the row of nozzles of FIG. 6,

FIG. 8 is a different embodiment of a hot runner nozzle,

FIG. 9 is a cross-sectional view taken along A—A in FIG. 8,

FIG. 10 is a cross-sectional view taken along B—B in FIG. 8,

FIG. 11 is a side view of another embodiment of a row of nozzles,

FIG. 12 is a top view of the row of nozzles of FIG. 11,

FIG. 13 is a is another embodiment of a hot runner nozzle,

FIG. 14 is a cross-sectional view taken along A—A in FIG. 13,

FIG. 15 is a cross-sectional view taken along B—B in FIG. 13,

FIG. 16 is yet another variant of a row of nozzles,

FIG. 17 is a cross-sectional view taken along C—C in FIG. 16,

FIG. 18 is a cross-sectional view taken along D—D in FIG. 16,

FIG. 19 is a top view of a battery of hot runner nozzles,

FIG. 20 is another embodiment of a hot runner nozzle assembly,

FIG. 21 is an enlarged portion of FIG. 20, partially in cross section,

FIG. 22 is a top view of the hot runner nozzle assembly of FIG. 20,

FIG. 23 is a cross-sectional view of a nozzle assembly mounted on a moldand

FIG. 24 is a top view of the hot runner assembly of FIG. 23, partiallyin cross section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A nozzle generally designated by reference numeral 10 in FIG. 1 is asubstantially T-shaped hot runner nozzle. It has a cross-sectionallyrectangular nozzle body 12 provided at its top end 13 with two lugs 16,17 forming opposite retainers for fixing to a hot runner mold ormanifold (not illustrated). The width b of the lugs 16, 17, which areintegral with the nozzle body 12, is equal to latter's width B so thatthe whole of the hot runner nozzle 10 forms a flat body K (see FIG. 2).

A central duct 22 for melt flow extending in an axial direction isprovided within the nozzle body 12. The duct 22, preferably a bore,comprises at its lower end a nozzle tip 26 whereby duct 22 is continuedout to a plane (not shown) of a mold cavity (not visible, either). Saidnozzle tip 26 is inserted into an end of the nozzle body 12, preferablyby a screw joint. However, it may serve the same purpose by way of beingan integral part of the nozzle body 12.

To improve coupling and sealing of flow duct 22 in respect of the hotrunner manifold, the nozzle body 12 carries between the lugs 16, 17 aring-shaped centering lug 23 which may be integral with the nozzle bodyor be part of a flow tube 24. The latter may be of a material other thanthat of the nozzle body 12 and is positively fitted therein as indicatedin FIG. 3. For example, tube 24 may be of a high-strength materialwhereas the nozzle body 12 is made of a highly thermoconductivematerial, whereby heat transfer is enhanced. However, it is alsopossible to manufacture tube 24 and nozzle body 12 as a single steelunit, production thus being simplified accordingly.

Two opposite plane lateral faces 14, 15 of nozzle body 12 serve asbearing faces each for flat heating means 28 that comprise an insulatinglamina consisting of a ceramic dielectric layer 40 directly applied tothe metal, of a heating layer 30 applied thereon which—asdiagrammatically indicated in FIG. 1—includes at least one meanderingheating conductor 32, and of an outer cover layer 50 which externallyshields and insulates both the heating conductor 32 and the underlyingdielectric layer 40.

The heating conductor 32 may be of any desired shape and, depending onthe output required, it can be applied to the insulating layer 40 indifferent configurations and various degrees of close packing. Thismakes it possible to attain a defined temperature distribution withinthe nozzle body 12 as desired. Preferably, meandering loops of theheating conductors 32 provided symmetrically on either side of nozzlebody 12 concentrate near the region of the nozzle tip 26 so that anadequate temperature can be produced and maintained right up to the moldcavity.

In order to be able to monitor or control the rise and profile of thetemperature within the nozzle body 12, at least one of its lateral faces14, 15 is provided with a thermosensor 60. Like the heating means 28,the thermosensor 60 has a thin monitoring layer 61 disposed in a commonplane with the heating layer 30 (FIG. 3). In the thin monitoring layer61, there is at least one continuous bifilar conducting path 62 which inthe lower region of nozzle body 12 extends close to the nozzle tip 26and, in the upper region of the nozzle body 12, terminates by way ofterminal contacts 64 at a lateral surface 18 of, for example, theright-hand lug 17.

On either side there, terminal contacts 34 are located for the heatingconductors 32 that run along the sides 14, 15 of nozzle body 12. It willbe seen in FIG. 2 that lug 17 recedes relative to the nozzle body 12toward its end in the region of the terminal contacts 34, 64 so that anelectrical plug (not shown) pushed onto lug 17 will not exceed theoverall thickness B of the nozzle body 12 and thus the overall thicknessof the flat body K. Therefore, the entire hot runner nozzle 10 includingthe connecting means is extremely slim. Alternatively it may be providedthat the terminal contacts 34, 64 for the heating conductors 32 or forthe thermosensor 60 engage the end face of lug 17.

The heating layer 30, the insulating layer 40, the cover layer 50,optionally an additional contact layer (not shown) and the monitoringlayer 61 are in succession integrally applied to the nozzle body 12 orto its lateral faces 14, 15 by direct coating, whereupon they are bakedunder firing conditions specific to the particular materials so that abonded lamina composite is formed whose overall thickness ranges from0.1 mm to 1.0 mm, preferably between 0.2 mm and 0.6 mm. Each heatinglamina composite 28 is undetachably applied as an integral part of thenozzle body 12 in full contact with its lateral faces 14, 15 so that anoptimal distribution of power output and heat is achieved with minimumdimensions.

A mechanical compressive pretension in the insulating dielectric layer40 is produced therein as it is baked, due to specific mismatchingbetween the linear coefficient of thermal expansion of the dielectriclayer 40 (TEC_(D)) and the linear coefficient of thermal expansion ofthe nozzle body 12 (TEC_(K)). Owing to such stress-tolerant joining, theinsulating layer 40 which is the supporting layer of the heating means28 can easily withstand pulsating internal pressure loads caused by thetechnology of the injection molding process, without cracks or otherdamage occurring in the heating means 28. Since the individual functionlayers 30, 40, 50, 61 of the lamina composite most firmly adhere to eachother by reason of the very similar structures specific to theirparticular materials, the heating means 28 features long-lastingresistance to even extreme mechanical and/or thermal loads.

A suitable coating method for applying the individual function layers30, 40, 50, 61 is film screen and thick-layer screen printing, i.e. useis preferably made of films or thick-layer pastes to be fired. Thisprocedure becomes especially economical when firing the dielectric layer40 is accompanied by inductive hardening of the nozzle body 12. It isimportant then to ensure that the respective firing conditions (such astemperature, residence time, cooling rate) are matched to the hardeningand annealing temperatures predetermined by the steel type used. Inparticular, the firing temperatures of subsequent layers must not exceedthe annealing temperatures of the metal in order to maintain itspreformed state of microstructure. Such adaptation can be achieved, forexample, by suitably varying the process parameters for the firingoperation. It is likewise possible to adapt the thick-layer pastes to beused to particular materials.

Alternatively, the layers 30, 40, 50, 61 of the heating means 28 can beapplied by blast coating or plasma coating to the bearing faces 14, 15of the pre-annealed nozzle body 12.

The heating means 28 is reliably protected against moisture absorptionby the direct layer application. Conventional heating devices comprisingtubular radiators or coil blocks are prone to moisture absorption inhygroscopic insulation materials, which leads not only to installationproblems but also to insulation trouble since the moisture absorbed maycause short circuits. In order to avoid this, regulators are requiredwhich provide start-up of the heating unit such that reduced power inputwill expel the moisture first. The heating means of the invention doesnot require this step. On the contrary, it is completely water-tight andis irremovably bonded to the flow duct so that hitherto indispensableinstallation and regulating expenditures are no longer incurred. This isadvantageous for the purchase and installation costs of a hot runnersystem.

Another alternative of the invention involves the use of a thermosensor60 which is not a layer but a replaceable plug-in unit inserted in aslot 66 formed in nozzle body 12. As shown in FIG. 4, this slot 66extends parallel to flow duct 22 in a laterally broadened region 20 ofnozzle body 12. In order to have easy lateral access to the connectingterminals 64 of the thermosensor 60, the top side 19 of lug 17 has anotch 67 which winds up in an end face 18′ of lug 17 for receiving anoffset end (not shown) of thermosensor 60, inclusive of terminals (FIG.5).

The nozzle assembly shown in FIG. 6 comprises a total of four hot runnernozzles 10 which are disposed in a row R as a densely packed parallelarrangement. Each of two hot runner nozzles 10 has a cross-sectionallyrectangular nozzle body 12 and these are interconnected at their upperends 13 via a bridge 21, preferably so as to be integral therewith. Thenozzle assembly thus forms a comb-like flat body K whose overallthickness D is substantially governed by the width B of the nozzlebodies 12. The latter carry two retainer arms by way of opposite lugs16, 17 for attachment of the assembly to a hot runner mold or manifold(not illustrated). Their width b corresponds to the width B of the flatbody K (cf. FIG. 2).

It will be seen that the hot runner nozzles 10 and their bodies 12,respectively, are very close together within the flat body K so that thespacing between the mold cavities can be relatively small, e.g. 8 mm orless, which is of great advantage primarily with the so-called outserttechnology. Due to their being interconnected only in the upper endregions 13, the nozzle bodies 12 can expand as necessary to compensatefor different thermal conductivities between the cold mold and the hotmanifold. Internal stresses within the flat body K are thus effectivelyavoided.

Two opposite plane lateral surfaces S of nozzle body 12, which ispreferably made of steel, serve as bearing faces for lamina heatingmeans 28 each, and the heating conductors 32 of each pair of adjacentheating means 28 in one plane are interconnected via the bridges 21 andare associated to common terminal contacts 34, 34′. The latter aresituated laterally on receding end regions of the lugs 16, 17 formed onthe respective outer hot runner nozzles 10. In this manner, the pairs ofheating means 28 shown in FIG. 6 can be assigned to separate heatingcircuits, and the heatings means 28 in the interior can be readilysupplied with current from an external source. Each of the outer hotrunner nozzles 10 is provided with a thermosensor 60 whose terminalcontacts 64 are likewise fixed on the lateral surfaces 18 of lugs 16,17.

Depending on the power requirement, the heating means 28 on a lateralsurface S of the flat body K can also be combined in a single heatingconductor 32 which starts and ends at terminal contacts 34 on only onelug 17. Power is supplied, for example, through a single heating circuitconnected laterally via lug 17. As the heating means 28 situatedopposite each other on the sides S provide a uniform temperaturedistribution within the flow duct 22, the total heater capacity may bereduced compared with a one-sided solution.

In the embodiment of FIGS. 6 and 7, four hot runner nozzles 10 arearranged in parallel side-by-side. However, an arbitrary plurality ofnozzles 10 may be arrayed next to each other in a row R, and with alarger number of nozzles 10 it may be advantageous—depending on thepower required—to provide heater connectors 34, 64 on either side of thenozzle row R.

Another embodiment of a hot runner nozzle 10 is illustrated in FIG. 8.The opposing lateral surfaces 14, 15 of the nozzle body 12 are eachprovided with a flat recess 36 whose depth is, for example, 0.4 mm. Eachrecess 36 is lined with a ceramics layer 40 having electrical insulatingproperties suitable for either low voltages or mains voltage. In thislined pocket or recess 36 a heating conductor 32 of a thin film F isplaced which includes a plurality of meandering loops near the nozzletip 26. The film F is composed of a resistor material and is narrower inthe region of the meandering loops than in the remaining regions of thenozzle body 12. In this way, power is deliberately concentrated in theregion of the nozzle tip 26. In order to fix the heating conductors 32in the recesses 36, ceramic pins 37 are provided which positively and/orfrictionally engage in corresponding holes 38 of the film F. As shown inFIG. 9, the ends of the heating conductors 32 extend into the lateralfaces 18 of the opposing retainers or lugs 16, 17, and the recesses 38likewise extending to that point are open towards the end faces 18′ oflugs 16, 17. This makes the heating conductors 32 provided on both sidesaccessible to terminal contacts (not shown) of a plug (likewise notvisible).

For external insulation of the overall flat heating assembly, theheating conductors 32 may be provided with a cover layer 50 or beterminated by cover plates 70 (FIGS. 9 and 10). The latter arepreferably of metal and carry on at least one side an insulating layer72 facing the respective heating means 28. Moreover, they are T-shapedso that all of the lateral lugs 16, 17 and their terminal contacts 34are externally protected. Attachment of the plates 70 is expedientlyeffected by means of screwed or welded bolts (not shown). Thusadditional surface pressure is attained so as to warrant reliablethermal contact between the film F and the nozzle body 12 or K,respectively.

In the embodiment shown in FIGS. 11 and 12, a plurality of closelypacked parallel hot runner nozzles 10 is situated in a row R, thebridges 21 between the nozzle bodies 12 being extremely thin. Thedistances between the nozzle tips 26 are reduced to a minimum right upto the region below the bridges 21, with remaining narrow slits 21′allowing for extremely small cavity spacings. Each lateral surface S ofthe flat body K, which is a single unit, has a recess 38 that extendsbeyond the bridges 21 and that accommodates a continuous heatingconductor 32 of a resistance film F. The film F or conductor 32commences at the lateral surface 18 of one of said lugs 16 and ends atthe lateral surface 18 of the other lug 17, both lugs 16, 17 receding intheir end regions in order to receive a plug. The cover plates 70provided on either side are likewise slotted in the region below thebridges 21 so that the upper compact region of the nozzle row R canexpand to a greater extent than the lower parts of the nozzle body 12,which in the region of the nozzle tips 26 form a seal in the cold mold.

Yet another embodiment of the invention is shown in FIGS. 13 to 15.Heating of the nozzle body 12 is effected via a tubular heater 28accommodated in a notch 29, which heating means commences in the firstlug 16 along the left edge of the lateral face 14 into the region of thenozzle tip 26, where it forms at least two symmetrical loops beforeextending up the right edge of the lateral face 14 and from there to thesecond lug 17. In the region where the heating means changes sides, theflow duct 22 recedes to create a step 22′ in order that the nozzle body12 would at this point withstand the pressure prevailing in flow duct22. Another important function of the step 22′ is to form a stop forscrewing-in the nozzle tip 26 whereby it is ensured that the totallength of the nozzle 10 will always remain the same after replacement ofthe nozzle tip 26. Readjustment of the mold is not necessary. Theheating means can be positively and/or frictionally forced into thenotch 29 or be held therein by soldering.

It will be seen from FIGS. 14 and 15 that the tubular heating means 28provided on either side 14, 15 of the nozzle body 12 terminate flushtherewith and are externally shielded by a cover plate 70 having thesame shape as nozzle body 12. For connecting the heating means 28 to oneor more heating circuits, terminals 34 protrude from the end faces 18′of lugs 16, 17.

FIGS. 16 to 18 show a row of nozzles R comprising three hot runnernozzles 10. The nozzle bodies 12 are combined to form a comb-like flatbody K containing a single heating means 28 on either side. Theirtubular heater 28 is situated in a notch 29 which extends across thebridge 21 over all three nozzle bodies. Electrical connection of theheating means 28 is effected through the lugs 16, 17 formed on the outerhot runner nozzles in the manner disclosed above.

Instead of accommodating tubular heaters 28, the notches 29 may readilycontain a cooling coil 42 through which a cooling agent can flow inorder to cool the nozzle body 12 or the flat body K. A cooling device28′ of this type keeps a flow melt in the ducts 22 at a constantly lowtemperature whereby the system can be used as a cold runner system. Itis also conceivable to form cooling coils 42 directly in the nozzlebodies 12, for example by means of bores. Alternatively, the notches 29may be sealingly covered by plates 70 so that a cooling agent candirectly flow in the notches 29.

A significant development of the invention is shown in FIG. 19 whichshows four or more nozzle rows R disposed parallel and in tightlyengaged packing side-by-side. By reason of the flat heating means 28 onthe respective lateral surfaces S of the nozzle rows R, the distancesbetween the nozzle tips 26 are relatively small also transversely to thelongitudinal direction of the rows R so that in such a battery ofnozzles, extremely small gating point spacings of a few millimeters onlycan be realized in both the X and Y directions. Indeed, very largegroups of gating points can thus be supplied with plastics material.Since the directly adjacent heating surfaces between the nozzle rows Rmutually influence each other, the total heating capacity may be furtherreduced, which is advantageous as to power consumption.

The mounting effort for a battery of nozzles according to the inventionis extremely simple and reduced to a minimum. Each nozzle row R israpidly and conveniently attached to a manifold or mold via the externallugs 16, 17 so that the usually time-consuming fixing of numerousindividual nozzles is no longer necessary. Depending on the desirednumber of nozzles 10, several rows R are simply placed next to eachother. The grouped heating means 28 can then be connected via lugs 16,17 to heating circuits to which they are associated. Unlike the priorart, the inner heating means 28 of the hot runner nozzles 10 areautomatically supplied with energy from outside without elaborate inputand output cables or connecting leads. The cost of installation isreduced to a minimum.

Depending on the embodiment of the heating means 28, cover plates 70 maybe provided between the various nozzle rows R, one cover plate then tobe insulated on both sides being sufficient for any two adjacent heatingmeans 28. Alternatively, only one heating unit 28 may be providedbetween any two rows of nozzles R at the lateral surfaces S of flat bodyK or at the lateral faces 14, 15 of nozzle body 12. The flow ducts 22situated on either side of a heating means 28 will then receive heatfrom a central source. In order to connect the nozzle rows R to thecover plates and to brace the rows R or their heating means 28 againsteach other, use is made of threaded bolts (not shown) which pass in-linethrough the flat bodies K at several points, or the battery of nozzlesis gripped from outside by one or more clamps (not illustrated, either).

Even smaller distances between the nozzle tips 26 are achieved if thenozzle rows R are staggered in a longitudinal direction and each hotrunner nozzle 10 laterally engages a depression formed in the region ofthe bridges 21.

The hot runner nozzle assembly illustrated in FIGS. 20 to 22 makes itpossible, in an advantageous manner, to carry out horizontal injectionmolding into a plurality of closely spaced adjacent mold cavities. Twonozzle rows R lie in a common horizontal plane E and are interconnectedin the region of their rear ends 13, preferably as a single unit. Thenozzle bodies 12 and the bridges 21 formed therebetween in alongitudinal direction L form a manifold block V that containsdistributing runners 82 which are in direct flow connection with theflow ducts 22 of the nozzle bodies 12.

A separate hot runner or cold runner nozzle 80 is mounted on themanifold V as central feeder which includes a tube 84 surrounded by acylindrical heater (not shown), the free end 85 of said tube being inlateral sealed engagement in a centric inlet orifice 83 of the manifoldV. This will guarantee that when the system is heated up or cooled down,axial expansion compensation is possible under good seal. It will berealized from FIG. 21 that the inlet orifice 83 is formed in a bushshoulder 87 mounted on the manifold V, whereby the expansion clearanceis favorably assisted.

FIGS. 23 and 24 show the situation upon installation of the hot runnernozzle block of FIG. 20 in a mold W that is divided into two halves W1and W2 exactly symmetrical to the plane E of the nozzle rows R. As thenozzles 10 are arranged in horizontal rows, the mold W may if desiredalso be divided vertically, i.e. symmetrically to the central nozzle 80.

The invention is not restricted to any of the embodiments describedabove but can be modified in variegated ways. For example, the lateralsurfaces 14, 15, S of the nozzle body 12 or the nozzle rows R mayportionwise be slightly curved, which can be particularly advantageouswhere adjacent rows of nozzles R are staggered in a longitudinaldirection and the individual nozzle bodies 12 engage depressions in thelateral surfaces S.

It will be seen that a nozzle 10 for an injection mold has a nozzle body12 which can be mounted on a mold or manifold wherein at least one duct22 for a melt flow is provided one end of which opens at, or in, anozzle tip 26. In order to be able to realize extremely small cavityspacings in two independent spatial directions, the nozzle body 12 hasat least one substantially plane lateral face 14, 15 which carries oraccommodates a heating and/or cooling means 28, 28′ for the melt flow,said means being facewise attached to, or placed against, said lateralface of the nozzle body 12. In a special embodiment, the nozzles 10within a nozzle row R are closely packed parallel to each other, and twoopposing lateral surfaces S of the nozzle row R are provided withheating and/or cooling means 28, 28′ suited to be connected in groups toa heating or cooling circuit via a common external connector 34.

All and any features and advantages, including structural details,spatial arrangements and process steps as evident from the claims,description and drawings, may be essential to the invention either aloneor in whatever combination.

List of Reference Symbols b width (lug) B width (nozzle body) D totalthickness (nozzle row) E plane F film K flat body L longitudinaldirection R row of nozzle S lateral surface V manifold (block) W mold W1mold half W2 mold half 10 hot/cold runner nozzle 12 nozzle body 13 topend 14, 15 lateral face (nozzle body) 16, 17 lugs 18 lateral face (lug)18′ end face (lug) 19 top face (lug) 20 broadening 21 bridge 21′ slot 22flow duct 22′ step 23 centering shoulder 24 tube 26 nozzle tip 28heating means 28′ cooling means 29 groove 30 heating layer 32 heatingconductor(s) 34, 34′ terminal contact 36 recess / pocket 37 pin 38 38hole (film) 40 insulating layer 42 cooling coil 50 cover layer 60thermosensor 61 monitoring layer 62 conductor(s) 64 terminal contact 66slot 67 groove 70 cover 72 insulating layer 80 feed unit 82 distributinglayer 83 inlet oriface 84 tube 85 free end 87 bush shoulder

What is claimed is:
 1. A nozzle (10) for an injection mold comprising anozzle body (12) including a mounting structure on an end thereof havinga longitudinal axis that is adapted to be mounted on a mold or manifold,the nozzle body including at least one duct (22) for a melt flow whichduct opens endwise at or in a nozzle tip (26), and comprising a heatingand/or cooling means (28, 28′) for the melt flow, the nozzle body (12)having at least one substantially plane lateral face (14, 15) which isgenerally parallel to the longitudinal axis of the mounting structureand supports or accommodates said heating and/or cooling means (28, 28′)in a full-faced engaging and/or joining arrangement, the at least onesubstantially plane lateral face (14, 15) being provided with the atleast one heating and/or cooling means.
 2. A nozzle (10) for aninjection mold comprising a nozzle body (12) adapted to be mounted on amold or manifold, the nozzle body including at least one duct (22) for amelt flow which duct opens endwise at or in a nozzle tip (26), andcomprising a heating and/or cooling means (28, 28′) for the melt flow,the nozzle body (12) having two opposing substantially plane lateralfaces (14, 15) each of which supporting or accommodating the heatingand/or cooling means (28, 28′) in a full-faced engaging and/or joiningarrangement, each of the substantially plane lateral faces (14, 15)being provided with the heating and/or cooling means (28, 28′). 3.Nozzle according to claim 1, wherein the nozzle (10) is a hot runnernozzle and to each hot runner nozzle (10) a healing means (28) isassociated comprising heating conductors (32), the power distribution oneach lateral surface (14, 15) being adapted to power requirements. 4.Nozzle according to claim 1, wherein the nozzle (10) is a cold runnernozzle and to each cold runner nozzle (10), a cooling means (28′) isassociated having cooling coils (42) for transporting a cooling orrefrigerating agent, the power distribution on each lateral surface (14,15) being adapted to power requirements.
 5. Nozzle according to claim 3,wherein the heating or cooling power is concentrated near the region ofthe nozzle tips (26).
 6. Nozzle according to claim 3, wherein theheating conductors (32) or the cooling coils (42) are at least partiallybifilar.
 7. Nozzle according to claim 1, wherein the heating and/orcooling means (28, 28′) provided on the lateral faces (14, 15) areassociated to at least one heating or cooling circuit.
 8. Nozzleaccording to claim 1, wherein a thermosensor (60) is associated to atleast one heating and/or cooling means (28, 28′).
 9. Nozzle according toclaim 8, wherein the thermosensor (60) is a component of the nozzle body(12) and at least one lateral face (14, 15) accommodates or supports thethermosensor (60) in a full-faced engaging or joining arrangement. 10.Nozzle according to claim 8, wherein the thermosensor (60) is insertedin a slot (66) formed in the nozzle body (12), which slot runs parallelto the flow duct (22) in the region of a broadened portion (20) of thenozzle body (12).
 11. Nozzle according to claim 1, wherein the nozzlebody (12) has at its upper end (13) at least one lateral lug (16, 17)whose width (b) does not exceed the width (B) of the nozzle body (12),terminals (34, 64) for the heating means (28), the cooling means (28′)and/or the thermosensor (60) being provided on, at or in one of saidtugs (16, 17).
 12. Nozzle according to claim 11, wherein the terminals(34, 64) are formed on the lateral faces (18) of the tugs (16, 17). 13.Nozzle according to claim 11, wherein at least one of the tugs (16, 17)is of less width than the nozzle body (12).
 14. Nozzle according toclaim 1, wherein the heating device (28) includes a lamina compositehaving at least two layers (30, 40), the heating conducts (32)consisting of a heating layer (30) applied to an insulating layer (40).15. Nozzle according to claim 14, wherein the insulating layer (40) is aceramic dielectric layer irremovably attached to the lateral face (14,15) and is, after at least one firing process, under compressivepretension relatively to said lateral face, the linear coefficient ofthermal expansion (TEC_(DE)) of the dielectric layer (40) being smallerthan the linear coefficient of thermal expansion (TEC_(K)) of thematerial of the lateral face (14, 15).
 16. Nozzle according to claim 14,wherein at least one electrically insulating cover layer (50) is appliedto the heating layer (30).
 17. Nozzle according to claim 14, wherein thethermosensor (60) is in the form of a layer and wherein the heatinglayer (30) and the monitoring layer (60) are disposed one over the otheror in the same plane.
 18. Nozzle according to claim 14, wherein theheating layer (30), the insulating layer (40), the cover layer (50), thecontact layer and the monitoring layer (60) form a lamina composite, andthe overall thickness of the lamina heating means (28) is between 0.1 mmand 1.0 mm, preferably between 0.2 mm and 0.6 mm.
 19. Nozzle accordingto claim 14, wherein the heating layer (30), the insulating layer (40),the cover layer (50), the contact layer and/or the monitoring layer (60)are baked films or baked thick-layer pastes, or they are applied to thelateral faces (14, 15) by means of blast coating or plasma coating. 20.Nozzle according to claim 14, wherein the heating layer (30) is a metalfoil attached to the insulating layer (40).
 21. Nozzle according toclaim 1, wherein the heating means (28) is a resistance wire or atubular heating unit.
 22. Nozzle according to claim 1, wherein eachheating and/or cooling means (28, 28′) is embedded in a notch (29) orrecess (36) in the respective lateral face (14, 16).
 23. Nozzleaccording to claim 1, wherein each heating and/or cooling means (28,28′) is flush with the nozzle body (12).
 24. Nozzle according to claim1, wherein each heating and/or cooling means (28, 28′) is provided witha cover (70).
 25. A nozzle assembly for injection molds comprising atleast two nozzles (10), each having a nozzle body (12) adapted to bemounted on a mold or manifold, each nozzle body including at least onemelt flow duct (22) which opens endwise at or in a nozzle tip (26), andcomprising a heating and/or cooling means (28, 28′) for the melt flow,wherein the nozzles (10) form a nozzle row (R) in the form of a flatbody (K) within which they are disposed in close packing parallel toeach other, the flat body (K) having at least one substantially planelateral surface (S) supporting or accommodating the heating and/orcooling means (28, 28′) in a full-faced engaging and/or joiningarrangement, the substantially plane lateral face (14, 15) beingprovided with the heating and/or cooling means (28, 28′), the totalthickness (D) of the flat body (K) being substantially determined by thethickness (width B) of the nozzle bodies (12).
 26. Nozzle assemblyaccording to claim 25, wherein at least one lateral lug (16, 17) of thenozzle body (12) is formed on an outer nozzle (10) of the row (R). 27.Nozzle assembly according to claim 25, wherein the heating means (28) orthe cooling means (28′) of adjacent nozzles (10) are interconnected andassociated to a common terminal (34).
 28. Nozzle assembly according toclaim 25, wherein the heating means (28) or the cooling means (28′) ofadjacent nozzles (10) are groupwise associated to separate heating orcooling circuits that have a common terminal (34).
 29. Nozzle assemblyaccording to claim 25, wherein at least two nozzle rows (R) are disposedside-by-side by surface match in a mold or manifold.
 30. Nozzle assemblyaccording to claim 29, wherein the nozzle rows (R) are in staggeredrelationship to each other.
 31. Nozzle assembly according to claim 25,wherein two rows of nozzles (R) are in a common plane (E) and areinterconnected at their rear ends, for example in a single unit. 32.Nozzle assembly according to claim 31, wherein the nozzle rows (R) havea common central feed unit (80) comprising distributing runners (82).33. Nozzle assembly according to claim 32, wherein the distributingrunners (82) are balanced.
 34. The nozzle of claim 1, further comprisingtwo opposing substantially plane lateral faces (14, 15), each of thesubstantially place lateral faces (14, 15) being provided with theheating and/or cooling means (28, 28′).
 35. The nozzle of claim 1,wherein the at least one substantially plane lateral face is part of anexposed exterior surface of the nozzle body.
 36. Nozzle according toclaim 4, wherein the cooling power is concentrated near the region ofthe nozzle tips (26).
 37. Nozzle according to claim 4, wherein thecooling coils (42) are at least partially bifilar.